While various types of exercise equipment exist, none appear more popular than stair climbing apparatus which simulates an escalator. This type of equipment exemplified by U.S. Pat. No. 4,687,195 utilizes pure mechanical braking apparatus which applies a braking torque to a sprocket-supported drive chain attached to the escalator stairs. In the past it has been the subject of some debate as to the safety of such devices, which use a mechanical lever-actuated braking system to provide a load to the shaft of one of the sprockets over which the drive chain runs. The reason for the concern is that in this type system an individual seeking to use the apparatus can mount the machine when the stairs are not in a braked condition. Upon so doing, the individual is thrown to the ground in front of the apparatus as the stair on which he places his foot fails to support him due to the unbraked condition of the apparatus.
While health clubs and the like require those utilizing exercise machinery to be thoroughly familiar with exercise equipment, accidents nonetheless happen when, for instance, mechanical braking apparatus is not initially actuated or even when it is partially engaged and the individual seeks to stop exercising. The result is however still the same, in that the individual can be thrown to the floor or otherwise injured due to the unbraked movement of the escalator.
In general, it will be appreciated, that while other exercise equipment may have a built-in loading system such as hydraulically-loaded exercise apparatus, escalator type equipment, while exceedingly beneficial in providing aerobic points to the user, is nonetheless considered relatively unsafe, due to the unique construction of the escalator which can result in the stairs running downward in an uncontrolled manner. If no load or very little load is initially placed on the stairs, this condition may not be noticed by the individual seeking to utilize the exercise equipment, with the result that it throws him to the ground, or otherwise results in injury.
There is however another problem with the utilization of mechanically-controlled escalator type exercise apparatus; and that is the ability to program or smoothly control the load placed on the stairs so as to simulate various types of athletic endeavor involving various types and difficulties of stair climbing. In the above patent, the stair climbing exercise is controlled by the braking torque applied by a pure mechanical brake system to the shaft of the sprocket engaged in controlling the speed of the escalator. Thus the machine cannot be easily computer-programmed.
In terms of exercise control, it will be appreciated that it is the weight of the individual acting against the retarding torque which controls the speed of exercise. The greater the torque, the slower the operation of the stairs and therefore the lower will be the amount of exercise involved. As will be noted, it is the stepping rate at which the individual exercises which is the measure of the exercise involved. By reducing the load on the sprocket shaft, the stairs move more quickly and the individual to maintain his position on the stair must move more rapidly, raising his body weight every time he takes a step. Thus reducing load increases exercise The ability to easily control the load and thus the exercise rate is thus not available when using pure mechanical braking of the stairs.
By way of further background, alternators have been utilized to provide load to various types of exercise equipment, although not exercise stairs. Here a large load resistor is placed across the alternator to provide a braking torque, with the resistor being a multi-tapped resistor under the control of a braking routine specified by the exercise program.
What will be appreciated is that such devices can never completely stop or clamp the rotary apparatus of the exercise machine to which the alternator is coupled. While the alternator can vary the braking torque, this device alone cannot lock up the exercise machine, making its use alone incapable of providing the safety of a completely immobilized and secured exercise machine.